The present invention relates to sprinkler units, and pertains particularly to improvements in subsurface mounted pop-up sprinkler units.
In my prior U.S. Pat. No. 4,796,809, entitled "TWO-STAGE POP-UP SPRINKLER", I disclose a pop-up sprinkler unit designed to be mounted beneath the soil surface, with a portion that pops-up through the soil and exposes the nozzle for distribution of the water. The pop-up unit and nozzle is protected by means of a sleeve as it extends up and retracts back through the soil to a position beneath the surface of the soil when not in use, where it is covered by either vegetation or a layer of soil. The sprinkler unit was designed for use on playing fields, and is fully retractable so as not to interfere with activities on the field.
Sprinkler units which retract into a housing in the ground when not in use, and which pop-up or extend from a housing to a position above the surface of the ground when water pressure is applied, are widely used in both residential and commercial applications. The most popular presently used sprinkler units are typically mounted in a protective well or housing, such that the top of the protective well of the sprinkler unit is typically at ground surface level. Such units are satisfactory for use around the periphery of a playing field where they are in an out-of-the-way place, such that they do not interfere with activity on the playing field. However, they are not satisfactory for use on playing fields.
In many applications, such as playing fields for sports and for golf courses and the like, it is desirable that the sprinkler unit be truly beneath the surface of the soil, so that it does not become an obstacle on the playing field. It is desirable that they be covered by either sod or soil, such that they do not interfere with normal activity on the playing field.
Attempts have been made in the past to solve this problem by providing subsoil mounted pop-up sprinkler units which pop-up through the soil to expose the nozzle. One such approach is illustrated in U.S. Pat. No. 1,853,805, issued Apr. 12, 1932 to Elder, entitled "Irrigating Sprinkler Apparatus". This patent discloses an irrigating apparatus wherein the tubular nozzle is reciprocally mounted in a housing mounted beneath the soil. The tubular nozzle has an open upper end and a check valve closing the upper end until the tubular nozzle has extended to its extended position, at which a check valve opens to permit the flow of water from the upper end of the nozzle. However, the unit is subject to high wear and to jamming in the extended position. It also lacks an effective distribution nozzle and means for protectively mounting such a nozzle.
Another attempts at such devices is disclosed in U.K. Patent No. 1256534, issued to Ede, and entitled "Improvements Relating to Spray Irrigation Units And Systems". This patent discloses a pop-up sprinkler unit wherein a first sleeve extends from a subsurface housing through a top surface of soil, and a final sleeve having ports therein extends from the first sleeve to distribute water. The housing and sleeves of the unit are disclosed as constructed of a plastic, such as PVC or the like. This unit is also subject to high wear and to jamming. The unit also fails to disclose a system which provides nozzles having good distribution.
The major problem with such known devices is that dirt, sand and grit from the surrounding soil get jammed between the relatively movable portions of the unit. Sand and grit also become embedded in the cylindrical telescoping sleeves and work past the seals into the area between the sleeve and housing. This results in the sleeve being jammed into position such that it will not retract. They also are subject to excessive wear between the sleeve and housing, resulting in excessive leaking.
In my above-identified prior patent, I disclosed a pop-up sprinkler unit having a spring biased and supported stainless steel sleeve disposed between telescoping outer and inner housings to protectively shield the nozzle as it extends from and retracts into the outer housing. While my prior device solves many of the prior art problems, it is still not whole satisfactory in that it is expensive to manufacture and the sleeve fails to optimally follow and protect the nozzle.
It is, therefore, desirable that a simple, effective and inexpensive pop-up sprinkler unit for subsurface mounting be available.